A method for preparing a catalyst for the hydrogenation of butyl butyrate

Abstract

The present application relates to the technical field of organic chemical waste liquid resource utilization, and discloses a preparation method of a butyl butyrate hydrogenation catalyst, which comprises the following steps: preparing a mesoporous gamma-Al2O3 carrier, modifying the mesoporous gamma-Al2O3 carrier by using a nitrogen-containing polymer, loading copper and zinc active components by a coprecipitation method, drying and calcining to obtain a catalyst precursor, and reducing to obtain the catalyst, so that a modified copper-based catalyst with high conversion rate and high butanol selectivity is provided by the preparation process of two steps of carrier modification and active loading, the catalyst is suitable for butyl octanol waste liquid butyl butyrate hydrogenation conditions, can effectively realize efficient resource utilization of waste liquid, the mesoporous carrier channel can provide a macromolecular diffusion channel, the nitrogen-containing modification layer on the surface of the carrier can reduce strong adsorption sites, the electron-deficient copper can inhibit the generation of carbon deposition precursors, and the catalyst has a multi-stage anti-carbon deposition structure design, and the synergistic effect of the three can significantly prolong the service life of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of organic chemical waste liquid resource utilization technology, specifically to a method for preparing a catalyst for the hydrogenation of butyl butyrate. Background Technology

[0002] Butanol and octanol (abbreviated as butanol and octanol) are important organic chemical raw materials, mainly used in the production of various plasticizers, acrylates, pharmaceutical intermediates, and other fine chemicals, with wide applications in plastics, rubber, and daily chemicals. In industrial production, butanol and octanol plants typically use propylene and syngas as raw materials, producing a mixture of n-butyraldehyde and isobutyraldehyde through a hydroformylation reaction. After separation, n-butyraldehyde is hydrogenated to produce butanol, and then condensed to form 2... Ethyl 2. Hexenal is further hydrogenated to prepare octanol. During the hydrogenation reaction, waste liquid containing butyl butyrate, butanol, octanol, and higher carbon esters is inevitably generated. Currently, the main method for treating the waste liquid from butanol / octanol plants is incineration, which not only wastes resources but also negatively impacts environmental protection and energy consumption control. Butyrate is a significant component of the waste liquid. Efficiently recovering butyl butyrate and hydrogenating it to butanol not only achieves resource recycling but also significantly reduces waste treatment costs, possessing significant economic and environmental value.

[0003] Copper-based catalysts are widely used in ester hydrogenation reactions due to their excellent selectivity for C=O bond hydrogenation. Traditional copper-zinc-aluminum catalysts are typically prepared using a co-precipitation method, but this method suffers from problems such as low dispersion of the active component, easy sintering of copper particles, and short catalyst lifetime. In recent years, researchers have attempted to improve catalyst performance through support modification. Chinese patent application CN108404919A discloses a copper-carbon catalyst for the liquid-phase hydrogenation of esters to fatty alcohols and its preparation method, using carbon materials as the support, copper as the active component, and zinc as a promoter, employing Cu... A carbon-coated copper-zinc catalyst was prepared by thermal decomposition of BTC precursor. This catalyst performed excellently in the pure butyl butyrate system, but the composition of butanol and octanol waste liquid is extremely complex, containing not only butyl butyrate but also heavy components such as C16 and above high carbon esters, ketones, and hydrocarbons. Direct application of this copper-carbon catalyst to the butanol and octanol waste liquid system has significant drawbacks, including: large molecular impurities are easily adsorbed and carbonized on the catalyst surface, clogging pores and leading to rapid deactivation; competitive adsorption of complex components reduces the selectivity of the target reaction; the high reaction temperature easily triggers thermal decomposition of high carbon components, generating non-condensable gases and olefins, affecting the butanol yield; and the carbon material support is mainly microporous, which is not conducive to macromolecular diffusion and has weak resistance to carbon deposition.

[0004] Therefore, developing a butyl butyrate hydrogenation catalyst with high activity, high selectivity, long lifespan, and suitability for complex butyrate and octanol waste liquid systems has significant industrial application value. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing a catalyst for the hydrogenation of butyl butyrate, which solves the problems of easy carbon deposition, general conversion rate, and low selectivity of copper-based catalysts in the hydrogenation conversion of butyl butyrate.

[0006] (II) Technical Solution To achieve the above objectives, the present invention discloses a method for preparing a catalyst for the hydrogenation of butyl butyrate, comprising the following steps: Step 1: Preparation of mesoporous γ Al2O3 support; Step 2: The mesoporous γ-ray membrane prepared in Step 1 Al2O3 support was ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. A nitrogen-containing polymer was added, the mixture was heated, and stirred at 50°C for 2 hours at a stirring rate of 500~800 r / min. The mixture was then filtered, washed with deionized water, dried at 80°C for 12 hours, and subjected to heat treatment. After natural cooling, the nitrogen-containing polymer-modified Al2O3 support was obtained. Step 3: The nitrogen-containing polymer-modified Al2O3 support prepared in Step 2 is ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. Copper nitrate, zinc nitrate, and deionized water are mixed to prepare a mixed salt solution. The mixed salt solution is slowly added dropwise to the nitrogen-containing polymer-modified Al2O3 support slurry. The mixture is stirred at 60°C while sodium carbonate solution is added dropwise to maintain the pH of the system at 7.5~8.0. After the addition is completed in 30 minutes, the mixture is stirred for 2 hours, allowed to stand for aging, filtered, and washed with deionized water at 60°C until no sodium ions remain as detected by flame photometry. The mixture is then dried at 110°C for 12 hours, calcined, and cooled to obtain the catalyst precursor. Step 4: Reduce the catalyst precursor in a reducing atmosphere to obtain a catalyst for the hydrogenation of butyl butyrate.

[0007] Preferably, the intermediate hole γ in step one The preparation method of Al2O3 support includes the following steps: aluminum nitrate is dissolved in deionized water to prepare an aluminum salt solution with a concentration of 1.0~1.5 mol / L. The solution is stirred, and then added dropwise to a mixed alkaline solution of sodium carbonate and sodium hydroxide with a molar ratio of 1:1 for precipitation. The precipitation temperature is controlled at 60~70℃ and the pH at 8.5~9.0. After precipitation, the solution is aged at 70℃ for 6 hours, filtered, and washed until neutral to obtain aluminum hydroxide precipitate. The aluminum hydroxide precipitate is dried at 110℃ for 12 hours and calcined at 550℃ for 4 hours to obtain mesoporous γ-ray crystals. Al2O3 support.

[0008] Preferably, the intermediate hole γ in step one The specific surface area of ​​the Al2O3 support is 180~250m². 2 / g, with mesopore sizes ranging from 5 to 15 nm.

[0009] Preferably, the nitrogen-containing polymer in step two is polyethyleneimine.

[0010] Preferably, the intermediate hole γ in step two The mass ratio of Al2O3 support to nitrogen-containing polymer is 1:(0.05~0.15).

[0011] Preferably, the heat treatment in step two is carried out in a tube furnace, in a nitrogen atmosphere, with the temperature increased from room temperature to 350°C at a heating rate of 2~4°C / min, and then kept at a constant temperature for 2~4 hours.

[0012] Preferably, in step three, the Cu in the mixed salt solution 2+ Zn 2+ The molar ratio is 1:(0.3~0.5).

[0013] Preferably, the temperature for static aging in step three is 60°C, and the static aging time is 12 hours.

[0014] Preferably, the roasting in step three is carried out in a muffle furnace, with the temperature rising from room temperature to 400°C at a rate of 2-4°C / min, and the roasting time is 5-6 hours.

[0015] Preferably, the reducing atmosphere in step four is a mixture of H2 and N2 gases, wherein the volume percentage of H2 is 5-10%, and the reduction is carried out at 300°C for 2-4 hours.

[0016] Preferably, in step four, the mass percentage of each component in the butyl butyrate hydrogenation catalyst is: 35-45% CuO, 15-25% ZnO, with the balance being Al2O3 and nitrogen-containing organic residues on the surface. The average particle size of the copper species in the butyl butyrate hydrogenation catalyst is 4-8 nm, and the copper species exhibit an electron-deficient state (Cu). δ+ ).

[0017] (iii) Beneficial technical effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The catalyst prepared in this invention is composed of mesoporous γ Al₂O₃, as a basic carrier, provides mechanical strength and a fundamental pore structure. Its three-dimensional, interconnected hierarchical pore structure offers rapid diffusion channels for macromolecular reactants, reducing diffusion limitations. In mesoporous γ-ray... A nitrogen-containing polymer modification layer is introduced onto the Al2O3 support surface, uniformly coated with a nitrogen-containing organic residue layer formed by the partial decomposition of polyethyleneimine. This modification layer is rich in nitrogen-containing functional groups such as -NH2 and -NH-. The lone pair electrons of the nitrogen atoms can transfer electrons to copper species, and the nitrogen-containing functional groups form coordination bonds with copper ions, providing an anchoring function. This inhibits the migration and aggregation of copper particles during calcination and reduction, effectively covering the strongly acidic sites on the support surface and reducing side reactions. This modification layer possesses a triple function of electron modulation, active component anchoring, and surface property modulation. The introduced copper-zinc active components are loaded onto the nitrogen-containing modification layer in the form of highly dispersed nanoparticles, forming an active center layer. Due to the electron-donating effect of the nitrogen-containing functional groups, the copper species exhibit an electron-deficient state (Cu). δ+ ), and conventional Cu 0 and Cu + Unlike other esters, this electron-deficient state exhibits a stronger adsorption and activation capacity for carbonyl groups. By optimizing the catalyst composition and structure, the catalyst's lifespan can be extended.

[0018] (2) In this invention, the steric hindrance effect of the polymer modification layer is utilized to reduce the adsorption and carbon deposition of macromolecular impurities, enabling the catalyst to maintain long-term stable activity when treating complex butanol and octanol waste liquids, thereby improving the hydrogenation selectivity of butyl butyrate. In complex waste liquid systems, highly selective hydrogenation of butyl butyrate is achieved, reducing the occurrence of side reactions. By improving the low-temperature activity of the catalyst, the hydrogenation reaction is completed at a lower temperature, avoiding thermal decomposition of high-carbon components and reducing side reactions. The lone pair electrons of nitrogen atoms in the nitrogen-containing polymer are used to transfer electrons to copper, forming electron-deficient copper (Cu). δ+ Because electron-deficient copper has a stronger ability to accept lone pairs of electrons from carbonyl oxygen, its adsorption strength is moderate, ensuring activation efficiency while avoiding side reactions caused by over-adsorption. Active hydrogen atoms attack the activated carbonyl carbon, forming a hemiacetal intermediate. This hemiacetal intermediate rapidly decomposes to generate one molecule of butyraldehyde and one molecule of butanol. Butyraldehyde immediately undergoes hydrogenation to generate a second molecule of butanol. This method enables efficient hydrogenation at relatively low temperatures, modulating the electronic state of the copper species. This electron-deficient state enhances the adsorption and activation ability of the carbonyl group in the ester group, thus improving intrinsic activity.

[0019] (3) This invention provides a modified copper catalyst with high conversion rate, high butanol selectivity, long single-pass lifetime, and resistance to impurity poisoning through a two-step preparation process of "carrier modification-active loading". It is suitable for the hydrogenation of butanol and octanol waste liquid and can effectively realize the efficient resource utilization of waste liquid. By modulating the electronic state of the catalyst, the reaction temperature is reduced, which effectively suppresses the thermal cracking side reaction of high carbon components in butanol and octanol waste liquid and improves the yield of the target product. Moreover, the introduced mesoporous carrier channels can provide macromolecular diffusion channels, the nitrogen-containing modification layer on the surface of the carrier can reduce strong adsorption sites, and the electron-deficient copper inhibits the formation of carbon deposition precursors. It has a multi-level anti-carbon deposition structure design, and the synergistic effect of the three significantly extends the catalyst lifetime. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example 1 A method for preparing a catalyst for the hydrogenation of butyl butyrate includes the following steps: Step 1: Preparation of mesoporous γ Al₂O₃ support: Aluminum nitrate was dissolved in deionized water to prepare an aluminum salt solution with a concentration of 1.0 mol / L. The solution was stirred, and then added dropwise to a mixed alkaline solution of sodium carbonate and sodium hydroxide in a 1:1 molar ratio for precipitation. The precipitation temperature was controlled at 60℃ and the pH at 8.5. After precipitation, the solution was aged at 70℃ for 6 hours, filtered, and washed until neutral to obtain aluminum hydroxide precipitate. The aluminum hydroxide precipitate was dried at 110℃ for 12 hours and calcined at 550℃ for 4 hours to obtain mesoporous γ-ray crystals. Al2O3 support; Step 2: Preparation of nitrogen-containing polymer-modified Al2O3 support: The mesoporous γ-ray polymer prepared in Step 1 is then used as a support. Al2O3 support was ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. A nitrogen-containing polymer, polyethyleneimine, was then added, containing mesoporous γ-rays. The mass ratio of Al2O3 support and nitrogen-containing polymer was 1:0.05. The mixture was heated to 50°C and stirred at a rate of 500 r / min for 2 h. After filtration, the mixture was washed with deionized water and dried at 80°C for 12 h. The mixture was then subjected to heat treatment in a tube furnace under a nitrogen atmosphere. The temperature was increased from room temperature to 350°C at a rate of 2°C / min and held at a constant temperature for 2 h. After natural cooling, the nitrogen-containing polymer-modified Al2O3 support was obtained. Step 3: Preparation of catalyst precursor: The nitrogen-containing polymer-modified Al2O3 support prepared in Step 2 is ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. Copper nitrate, zinc nitrate, and deionized water are mixed to prepare a mixed salt solution, wherein the mixed salt solution contains Cu 2+ Zn 2+ The molar ratio of the mixed salt solution was 1:0.3. The mixed salt solution was slowly added dropwise to the nitrogen-containing polymer-modified Al2O3 support slurry. The mixture was stirred at 60°C, and sodium carbonate solution was added dropwise to maintain the pH of the system at 7.5. After the addition was completed in 30 min, the mixture was stirred for 2 h, and then allowed to stand for aging at 60°C for 12 h. The mixture was filtered and washed with deionized water at 60°C until no sodium ions were detected by flame photometry. The mixture was then dried at 110°C for 12 h and calcined in a muffle furnace at a heating rate of 2°C / min from room temperature to 400°C for 5 h. After cooling, the catalyst precursor was obtained. Step 4: Preparation of butyl butyrate hydrogenation catalyst: The catalyst precursor is reduced in a reducing atmosphere, which is a H2 / N2 mixed gas, wherein the volume percentage of H2 is 5%. The reduction is carried out at 300℃ for 2 hours to obtain the butyl butyrate hydrogenation catalyst. The mass percentage of each component in the catalyst is: 35% CuO, 15% ZnO, and the balance is Al2O3 and nitrogen-containing organic residues on the surface.

[0022] Example 2 A method for preparing a catalyst for the hydrogenation of butyl butyrate includes the following steps: Step 1: Preparation of mesoporous γ Al₂O₃ support: Aluminum nitrate was dissolved in deionized water to prepare an aluminum salt solution with a concentration of 1.2 mol / L. The solution was stirred, and then added dropwise to a mixed alkaline solution of sodium carbonate and sodium hydroxide (molar ratio 1:1) for precipitation. The precipitation temperature was controlled at 65℃ and the pH at 8.8. After precipitation, the solution was aged at 70℃ for 6 hours, filtered, and washed until neutral to obtain aluminum hydroxide precipitate. The aluminum hydroxide precipitate was dried at 110℃ for 12 hours and calcined at 550℃ for 4 hours to obtain mesoporous γ-ray crystals. Al2O3 support; Step 2: Preparation of nitrogen-containing polymer-modified Al2O3 support: The mesoporous γ-ray polymer prepared in Step 1 is then used as a support. Al2O3 support was ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. A nitrogen-containing polymer, polyethyleneimine, was then added, containing mesoporous γ-rays. The mass ratio of Al2O3 support and nitrogen-containing polymer was 1:0.1. The mixture was heated to 50°C and stirred at a rate of 600 r / min for 2 h. After filtration, the mixture was washed with deionized water and dried at 80°C for 12 h. The mixture was then subjected to heat treatment in a tube furnace under a nitrogen atmosphere. The temperature was increased from room temperature to 350°C at a rate of 3°C / min and held at a constant temperature for 3 h. After natural cooling, the nitrogen-containing polymer-modified Al2O3 support was obtained. Step 3: Preparation of catalyst precursor: The nitrogen-containing polymer-modified Al2O3 support prepared in Step 2 is ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. Copper nitrate, zinc nitrate, and deionized water are mixed to prepare a mixed salt solution, wherein the mixed salt solution contains Cu 2+ Zn 2+ The molar ratio of the mixed salt solution was 1:0.4. The mixed salt solution was slowly added dropwise to the nitrogen-containing polymer-modified Al2O3 support slurry. The mixture was stirred at 60°C, and sodium carbonate solution was added dropwise to maintain the pH of the system at 7.8. After the addition was completed in 30 min, the mixture was stirred for 2 h, and then allowed to stand for aging at 60°C for 12 h. The mixture was filtered and washed with deionized water at 60°C until no sodium ions were detected by flame photometry. The mixture was then dried at 110°C for 12 h and calcined in a muffle furnace at a heating rate of 3°C / min from room temperature to 400°C for 5.5 h. After cooling, the catalyst precursor was obtained. Step 4: Preparation of butyl butyrate hydrogenation catalyst: The catalyst precursor is reduced in a reducing atmosphere, which is a H2 / N2 mixed gas, wherein the volume percentage of H2 is 8%. The reduction is carried out at 300℃ for 3 hours to obtain the butyl butyrate hydrogenation catalyst. The mass percentage of each component in the catalyst is: 40% CuO, 20% ZnO, and the balance is Al2O3 and nitrogen-containing organic residues on the surface.

[0023] Example 3 A method for preparing a catalyst for the hydrogenation of butyl butyrate includes the following steps: Step 1: Preparation of mesoporous γ Al₂O₃ support: Aluminum nitrate was dissolved in deionized water to prepare an aluminum salt solution with a concentration of 1.5 mol / L. The solution was stirred, and then added dropwise to a mixed alkaline solution of sodium carbonate and sodium hydroxide (molar ratio 1:1) for precipitation. The precipitation temperature was controlled at 70℃ and the pH at 9.0. After precipitation, the solution was aged at 70℃ for 6 hours, filtered, and washed until neutral to obtain aluminum hydroxide precipitate. The aluminum hydroxide precipitate was dried at 110℃ for 12 hours and calcined at 550℃ for 4 hours to obtain mesoporous γ-ray crystals. Al2O3 support; Step 2: Preparation of nitrogen-containing polymer-modified Al2O3 support: The mesoporous γ-ray polymer prepared in Step 1 is then used as a support. Al2O3 support was ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. A nitrogen-containing polymer, polyethyleneimine, was then added, containing mesoporous γ-rays. The mass ratio of Al2O3 support and nitrogen-containing polymer was 1:0.15. The mixture was heated to 50°C and stirred at 800 r / min for 2 h. After filtration, the mixture was washed with deionized water and dried at 80°C for 12 h. The mixture was then subjected to heat treatment in a tube furnace under a nitrogen atmosphere. The temperature was increased from room temperature to 350°C at a rate of 4°C / min and held at a constant temperature for 4 h. After natural cooling, the nitrogen-containing polymer-modified Al2O3 support was obtained. Step 3: Preparation of catalyst precursor: The nitrogen-containing polymer-modified Al2O3 support prepared in Step 2 is ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. Copper nitrate, zinc nitrate, and deionized water are mixed to prepare a mixed salt solution, wherein the mixed salt solution contains Cu 2+ Zn 2+ The molar ratio of the mixed salt solution was 1:0.5. The mixed salt solution was slowly added dropwise to the nitrogen-containing polymer-modified Al2O3 support slurry. The mixture was stirred at 60°C, and sodium carbonate solution was added dropwise to maintain the pH of the system at 8.0. After the addition was completed in 30 min, the mixture was stirred for 2 h, and then allowed to stand for aging at 60°C for 12 h. The mixture was filtered and washed with deionized water at 60°C until no sodium ions were detected by flame photometry. The mixture was then dried at 110°C for 12 h and calcined in a muffle furnace at a heating rate of 4°C / min from room temperature to 400°C for 6 h. The mixture was then cooled to obtain the catalyst precursor. Step 4: Preparation of butyl butyrate hydrogenation catalyst: The catalyst precursor is reduced in a reducing atmosphere, which is a H2 / N2 mixed gas, wherein the volume percentage of H2 is 10%, and the reduction is carried out at 300℃ for 4 hours to obtain the butyl butyrate hydrogenation catalyst. The mass percentage of each component in the catalyst is: 45% CuO, 25% ZnO, and the balance is Al2O3 and nitrogen-containing organic residues on the surface.

[0024] Comparative Example 1 A method for preparing a catalyst, compared with Example 2, differs in that it contains mesoporous γ The Al2O3 support was not modified with nitrogen-containing polymers; mesoporous γ-rays were used directly. The Al2O3 support was used as the catalyst support, and the other components and preparation methods were completely consistent with those in Example 2.

[0025] Comparative Example 2 A method for preparing a catalyst, compared with Example 2, differs in that no support is introduced and the catalyst is prepared directly, while the other components and preparation method are completely consistent with Example 2.

[0026] The catalyst preparation method in this comparative example includes the following steps: Step 1: Mix copper nitrate, zinc nitrate, and deionized water to prepare a mixed salt solution, wherein the mixed salt solution contains Cu 2+ Zn 2+ The molar ratio was 1:0.4. The mixture was stirred at 60℃ while sodium carbonate solution was added dropwise to maintain the pH of the system at 7.8. After the addition was completed in 30 min, the mixture was stirred for 2 h and then allowed to stand for aging at 60℃ for 12 h. The mixture was then filtered and washed with deionized water at 60℃ until no sodium ions were detected by flame photometry. The mixture was then dried at 110℃ for 12 h and calcined in a muffle furnace at a heating rate of 3℃ / min from room temperature to 400℃ for 5.5 h. After cooling, the catalyst precursor was obtained. Step 2: The catalyst precursor is reduced in a reducing atmosphere, which is a mixture of H2 / N2 gas, with H2 accounting for 8% of the volume. The reduction is carried out at 300℃ for 3 hours to obtain the catalyst.

[0027] The catalysts prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to relevant performance tests, as follows: The process steps for treating butyrate hydrogenation to butanol from butanol and octanol waste liquid using the prepared catalyst are as follows: (1) Pretreatment of waste liquid: The waste liquid from the butanol and octanol unit is distilled, and the C4~C10 light components are collected from the top of the column, and the C12 and above heavy components are collected from the bottom of the column. The material is collected in the middle section of the column, and the components with too small or too large molecular weights are removed to obtain hydrogenation feedstock; (2) Hydrogenation reaction: The hydrogenation feedstock is pressurized to 2~3 MPa by a booster pump and mixed with high-pressure hydrogen (the mass flow ratio of hydrogen to feedstock is 0.1~0.15). It is then preheated to 120~150℃ in a preheater. The preheated material is then fed into a fixed-bed hydrogenation reactor. The reactor is filled with the catalyst prepared in this invention. The reaction conditions are: temperature 160~190℃, pressure 4MPa, liquid hourly space velocity 2h. -1 (3) Product separation: The material after hydrogenation reaction enters the gas-liquid separator to remove residual hydrogen and obtain crude alcohol liquid. The crude alcohol liquid is sent to the distillation column for separation. The n-butanol product (purity ≥99.5%) is collected from the top of the column, and octanol and a small amount of heavy components are collected from the bottom of the column and returned to the waste liquid treatment system for recycling. The composition of the product is analyzed by gas chromatography-mass spectrometry (GC-MS), the conversion rate of butyl butyrate and the selectivity of n-butanol are calculated, and the stability of continuous operation for 1000h is evaluated at the same time. The test results are shown in Table 1: Table 1 As shown in Table 1, the catalysts corresponding to Examples 1-3 exhibit significantly improved stability in treating butanol and octanol wastewater due to the anchoring effect and anti-carbon deposition function of the nitrogen-containing polymer modification layer. They demonstrate high butyl butyrate conversion and high selectivity for n-butanol, and maintain excellent butyl butyrate conversion even after 1000 hours, indicating good stability. The nitrogen-containing modification layer covers the strongly acidic sites on the alumina surface, reducing the adsorption and poisoning of trace impurities in the wastewater. In Comparative Example 1, the lack of nitrogen-containing polymer modification and the absence of an anchoring structure on the support surface led to a significant decrease in conversion and selectivity, resulting in poor overall performance. Comparative Example 2, lacking a support, suffered from severe particle agglomeration, extremely low dispersion, missing pore structure, high material diffusion resistance, and extremely poor resistance to impurities and carbon deposition, exhibiting the worst catalytic performance.

[0028] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for preparing a catalyst for the hydrogenation of butyl butyrate, characterized in that: Includes the following steps: Step 1: Preparation of mesoporous γ Al2O3 support; Step 2: The mesoporous γ-ray membrane prepared in Step 1 Al2O3 support was ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. A nitrogen-containing polymer was added, the mixture was heated, and stirred at 50°C for 2 hours at a stirring rate of 500~800 r / min. The mixture was then filtered, washed with deionized water, dried at 80°C for 12 hours, and subjected to heat treatment. After natural cooling, the nitrogen-containing polymer-modified Al2O3 support was obtained. Step 3: The nitrogen-containing polymer-modified Al2O3 support prepared in Step 2 is ultrasonically dispersed in deionized water to prepare a slurry with a solid content of 20%. Copper nitrate, zinc nitrate, and deionized water are mixed to prepare a mixed salt solution. The mixed salt solution is slowly added dropwise to the nitrogen-containing polymer-modified Al2O3 support slurry. The mixture is stirred at 60°C while sodium carbonate solution is added dropwise to maintain the pH of the system at 7.5~8.

0. After the addition is completed in 30 minutes, the mixture is stirred for 2 hours, allowed to stand for aging, filtered, and washed with deionized water at 60°C until no sodium ions are detected by flame photometry. The mixture is then dried at 110°C for 12 hours, calcined, and cooled to obtain the catalyst precursor. Step 4: Reduce the catalyst precursor in a reducing atmosphere to obtain a catalyst for the hydrogenation of butyl butyrate.

2. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: Step 1 Intermediate Hole γ The preparation method of Al2O3 support includes the following steps: aluminum nitrate is dissolved in deionized water to prepare an aluminum salt solution with a concentration of 1.0~1.5 mol / L. The solution is stirred, and then added dropwise to a mixed alkaline solution of sodium carbonate and sodium hydroxide with a molar ratio of 1:1 for precipitation. The precipitation temperature is controlled at 60~70℃ and the pH at 8.5~9.

0. After precipitation, the solution is aged at 70℃ for 6 hours, filtered, and washed until neutral to obtain aluminum hydroxide precipitate. The aluminum hydroxide precipitate is dried at 110℃ for 12 hours and calcined at 550℃ for 4 hours to obtain mesoporous γ-ray crystals. Al2O3 support.

3. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: The nitrogen-containing polymer in step two is polyethyleneimine.

4. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: Step two intermediate hole γ The mass ratio of Al2O3 support to nitrogen-containing polymer is 1:(0.05~0.15).

5. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: In step two, the heat treatment is carried out in a tube furnace under a nitrogen atmosphere, with the temperature increased from room temperature to 350°C at a rate of 2-4°C / min, and then kept at a constant temperature for 2-4 hours.

6. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: Cu in the mixed salt solution in step three 2+ Zn 2+ The molar ratio is 1:(0.3~0.5).

7. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: In step three, the temperature for static aging is 60℃, and the static aging time is 12 hours.

8. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: In step three, the calcination is carried out in a muffle furnace, with the temperature rising from room temperature to 400°C at a rate of 2-4°C / min, and the calcination time is 5-6 hours.

9. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: In step four, the reducing atmosphere is a mixture of H2 and N2 gases, with H2 accounting for 5-10% of the volume, and the reduction is carried out at 300℃ for 2-4 hours.

10. The method for preparing a catalyst for the hydrogenation of butyl butyrate according to claim 1, characterized in that: The mass percentages of each component in the catalyst used for hydrogenation of butyl butyrate in step four are: 35-45% CuO, 15-25% ZnO, and the balance is Al2O3 and nitrogen-containing organic residues on the surface.

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